Demo Circuit 1265 QUICK START GUIDE LTC3220/LTC3220-1 LTC3220/LTC3220-1 360mA Universal 18-Channel LED Driver DESCRIPTION 2 complished via an IC serial interface. See the WARNING LTC3220/LTC3220-1 data sheet for more information on this process. There are 64 dimming states available for Do not look directly at operating LED. the universal LEDs. This circuit produces light that can damage eyes. The charge pump optimizes efficiency based on the volt- age across the LED current sources. The part powers up Demonstration circuit 1265 is a 360mA Universal 18- in 1x mode and will automatically switch to boost mode Channel LED Driver with twelve white LEDs and two RGB whenever any enabled LED current source begins to drop LEDs featuring the LTC3220/LTC3220-1. out. The first dropout switches the part to 1.5x mode and The LTC3220/LTC3220-1 is a low noise charge pump a subsequent dropout switches the part into 2x mode. designed to drive 18 universal LED (ULED) current The part resets to 1x mode whenever a data byte is up- 2 sources. The LTC3220/LTC3220-1 requires only five dated via the I C port. small ceramic capacitors to form a complete LED power Design files for this circuit board are available. Call supply and current controller. the LTC factory. The maximum display currents are set with an internal L, LTC, LTM, LT are registered trademarks of Linear Technology Corporation. Other product precision current reference. On/Off blinking, gradation, names may be trademarks of the companies that manufacture the products. intensity, and a software controlled shutdown are ac- PERFORMANCE SUMMARY Specifications are at T = 25C A PARAMETER CONDITIONS MIN TYP MAX UNITS Input Supply Range (V ) 2.9 5.5 V IN VIN Shutdown Current 3.2 7 uA DV Operating Voltage 1.5 5.5 V CC DV Shutdown Current 1 A CC CPO Regulation Voltage 1.5x Mode, I = 20mA 4.5 V CPO 2x Mode, I = 20mA 5.03 V CPO Full-Scale LED Current ULED = 1V 18 20 22 mA Absolute Maximum LED Current Strong GPO Mode, external current limit needed 25 mA Minimum (I ) LED Current Step 0.314 mA LSB Minimum Programmable Current ULED Data Register Programmed to 0b00000001 0.395 mA LED Current Matching Any Two Outputs, 50% Full-Scale 1.5 % LED Dropout Voltage I = Full-Scale 120 mV LED LED Turn-on Delay From Stop Bit, Part Enabled 4 uS 1LTC3220/LTC3220-1 QUICK START PROCEDURE Demonstration circuit 1265 is easy to set up to evaluate 3. Connect DC1265 to the DC590 USB Serial Controller the performance of the LTC3220/LTC3220-1. Refer to using the supplied 14-conductor ribbon cable as Figure 1 for proper measurement equipment setup and shown in Figure 1. follow the procedure below: 4. With power off, connect a 5V, 1A power supply to VIN NOTE. When measuring the input or output voltage ripple, care and GND with a series ammeter and a voltmeter as must be taken to avoid a long ground lead on the oscilloscope shown in Figure 1. probe. Measure the input or output voltage ripple by touching the probe tip directly across the VIN and GND or CPO and GND Turn on and set the input power supply between 2.9 5. terminals. See Figure 2 for proper scope probe technique. 5.5V. The DC1265 has an extra 4.7uF de-coupling ca- TM 1. Refer to the DC590 Quick Start Guide for QuikEval pacitor between VIN and GND to help accommodate setup and software installation details. long VIN source lead lengths. The DC590 board gets its power from the USB cable. 2. Make sure the USB cable is connected between the NOTE. Make sure that the input voltage does not exceed 6V. computer and the DC590 controller board. NOTE. If using the DC590B board, a specific DVCC voltage level 6. Run the QuikEval program. The program detects the may be selected. This is done by setting the VCCIO jumper on the DC1265 and displays the LTC3220 control window DC590 board to one of the following settings: 3.3V, 5V, removed (shown in Figure 5). for 2.7V or set to external if an external supply is desired to be used. 2